tentacle

tentacle /n./ A covert pseudo, sense 1. An artificial
identity created in cyberspace for nefarious and deceptive
purposes. The implication is that a single person may have
multiple tentacles. This term was originally floated in some
paranoid ravings on the cypherpunks list (see cypherpunk), and
adopted in a spirit of irony by other, saner members. It has since
shown up, used seriously, in the documentation for some remailer
software, and is now (1994) widely recognized on the net.